Supreme Court says police can't attach GPS monitors without a warrant.

The Supreme Court has ruled police need a search warrant to track a suspect with GPS.

The justices heard arguments last year in the case of a nightclub owner convicted of drug conspiracy.

Police in Washington, DC had attached a GPS tracking system to his car and followed his movements.

The GPS led investigators to a stash of money and drugs.

Monday's unanimous ruling states they needed a search warrant to put the technology on the car.

A federal appeals court overturned the nightclub owner's conviction.

The decision by the Supreme Court upholds that lower court ruling.